There is currently a strong trend toward downsizing existing structures and fabricating smaller structures. This process is commonly referred to as microfabrication. One area in which microfabrication has had a sizeable impact is in the microelectronic area. In particular, the downsizing of microelectronic structures has generally allowed the structures to be less expensive, have higher performance, exhibit reduced power consumption, and contain more components for a given dimension. Although microfabrication has been widely active in the electronics industry, it has also been applied to other applications such as biotechnology, optics, mechanical systems, sensing devices, and reactors.
One method employed in the microfabrication process is imprint lithography. Imprint lithography is typically utilized to pattern thin films on a substrate material with high resolution. The thin films patterned can be dielectrics, semiconductors, metals or organics and can be patterned as thin films or individual layers. Imprint lithography is particularly useful for patterning devices in a roll-to roll environment since imprint lithography is not as sensitive to planarity as conventional photolithography. Additionally, imprint lithography has a higher throughput and can handle wider substrates.
Typically, the fabrication of an electronic device will require several patterning steps that often must be aligned with each other with a degree of accuracy approaching or even exceeding the minimum feature size. In conventional photolithography, optical alignment marks are used to guarantee alignment between successive patterning steps. Although, it is possible to use optical alignments in a roll-to-roll process it is not practical for several reasons. First, it adds additional complexity since the fundamental imprint lithography process is not optical. Next, the lack of planarity of the substrate in a roll-to-roll environment causes difficulties in the accuracy with which optical alignments can be made due to depth of field restrictions and other optical aberrations. Finally, the flexible substrates used in roll-to-roll processing may experience dimensional changes due to variations in temperature, humidity, or mechanical stress. These contractions or dilations of one patterned layer with respect to the next may make alignments of a large area impossible.
Accordingly, what is needed is a method and system for fabricating a device that overcomes the above referenced problems. The method and system should be simple, cost effective and capable of being easily adapted to existing technology. The present invention addresses these needs.